Modern channels of trade, frequently including international supply and distribution chains, are often highly complex, span thousands of miles and multiple transportation modes and convey valuable goods from sources to destinations all over the world. A typical supply and distribution chain often begins at a manufacturing plant, where goods are fabricated and loaded into shipping containers for transportation by truck or train to a sea port. At the port, the shipping containers are loaded onto ships and transported across various bodies of water. Once they reach their destination, the ships are unloaded, and the shipping containers again shipped overland by truck or train to one or more rail yards and then to distribution centers. The goods are then typically broken up into smaller lots, perhaps into separate pallets or boxes and loaded onto trucks for their final destinations, which are often retail stores or other manufacturing plants.
It is apparent that the risk of misplacement, loss or theft of the goods abounds given the many static sites and transportation modes employed in a typical supply and distribution chain. The risk of sabotage or terrorism also looms as shipping containers lie idle in ports, yards and distribution centers. Sophisticated, expensive and labor-intensive tracking systems exist for identifying and locating goods in such chains. However, these systems fail to offer end-to-end tracking and require excessive human intervention and maintenance, severely diminishing their effectiveness. As a result, despite the sophistication of such systems and the sheer amount of money, time and effort that are spent on them, goods are still lost, misplaced or stolen every day.